Bono is reportedly the world's richest rock star, in large part due to a fat stake in Facebook he bought with an investment group in 2009, according to the London Mirror.

Bono, 55, and an investment group he co-founded, Elevation Partners, paid about $85.9 million for a 2.3% share in the social media company when it went public six years ago that has grown to be worth more than $1.4 billion, said the paper, observing that investment "has earned him more in the last six years than the whole of his incredible music career."

The Dubliner's wealth is now greater than that of Sir Paul McCartney, who is worth about $1.1 billion, and Madonna, who is worth about $798 million, according to the paper.

Bono's good fortune with Facebook stock comes on the heels of news earlier this month that Edun Apparel, the ethical clothing firm he and his wife Ali Hewson, had lost more than $64.4 million since the couple founded it in 2005, despite a narrowing of losses in recent years.

Bono uses Facebook, too: The singer took to the social network to apologize in a video clip last October, after he was bombarded with criticism for releasing U2's album, "Songs of Innocence," automatically into people's iTunes accounts.